April 21: Deputy Interior Secretary David Hayes is dispatched to the Gulf to coordinate the government’s response.

April 22: The rig sinks. President Obama briefed in the Oval Office by members of his Cabinet and other advisers, including Homeland Security Secretary Janet Napolitano, Coast Guard Adm. Thad Allen, Interior Secretary Ken Salazar and economic adviser Larry Summers. The government is monitoring the spill, but the focus is still largely search and rescue.

April 23: Coast Guard Rear Adm. Mary Landry says no oil appears to be leaking from the undersea wellhead or at the water’s surface.

April 24: Leak reported; oil is estimated to be leaking at the rate of 1,000 barrels a day.

April 29: Coast Guard says leak may be five times greater than earlier estimate: 5,000 barrels a day. Louisiana Gov. Bobby Jindal declares state of emergency. Napolitano declares this a “spill of national significance,” allowing additional resources to flow to the Gulf from around the country.

April 30: Napolitano and Salazar visit the Gulf region. Obama says he continues to believe in increased domestic oil production but adds it must be done “responsibly” to protect both workers and environment.

May 1: Allen, the Coast Guard commandant, is named national incident commander.

May 2: Obama visits Coast Guard station in Venice, La. Federal government bans fishing for at least 10 days in a large swath of the Gulf between the mouth of the Mississippi River and Pensacola Bay.

May 3: BP CEO Tony Hayward tells NPR his company will pay for the cleanup and any “legitimate” legal claims.